diff --git a/techlibs/xilinx/synth_xilinx.cc b/techlibs/xilinx/synth_xilinx.cc
index 0a30848aa..c18c3918f 100644
--- a/techlibs/xilinx/synth_xilinx.cc
+++ b/techlibs/xilinx/synth_xilinx.cc
@@ -194,7 +194,7 @@ struct SynthXilinxPass : public ScriptPass
 				continue;
 			}
 			if (args[argidx] == "-widemux" && argidx+1 < args.size()) {
-				widemux = atoi(args[++argidx].c_str());
+				widemux = std::stoi(args[++argidx]);
 				continue;
 			}
 			if (args[argidx] == "-abc9") {